As used herein, the term “organic electronic device” refers to a device that requires the exchange of an electronic charge between an electrode and an organic material using holes and/or electrons. Organic electronic devices can be largely classified according to operational principle into the following two types. One type is an electronic device having a configuration in which an exciton is formed in an organic material layer by the entry of photons into the device from an external light source, and is then separated into an electron and a hole, which are transferred to different electrodes to create a current source (voltage source), and the other type is an electric device having a configuration in which a voltage or current is applied to two or more electrodes to inject a hole and/or an electron into an organic semiconductor positioned at the interface between the electrodes, and the device is operated using the injected electron and hole.
Examples of the organic electronic device include an organic light-emitting device, an organic solar cell, an organic photo-conductor (OPC), an organic transistor and the like, all of which require a hole-injecting or hole-transporting material, an electron-injecting or electron-transporting material or a light emitting material to drive the device. Hereinafter, the organic light-emitting device will be mainly and specifically described, but in the above-mentioned organic electronic devices, the hole-injecting material, hole-transporting material, electron-injecting material, electron-transporting material, and light-emitting material function according to a similar principle.
In general, the term “organic light-emitting phenomenon” refers to a phenomenon in which electrical energy is converted to light energy using an organic material. The organic light-emitting device that uses the organic light-emitting phenomenon usually has a structure comprising an anode, a cathode and an organic material layer interposed therebetween. Herein, the organic layer often has a multilayer structure consisting of a plurality of layers made of different materials in order to increase the efficiency and stability of the organic light-emitting device. For example, the organic material layer may consist of a hole-injecting layer, a hole-transporting layer, a light-emitting layer, an electron-transporting layer, an electron-injecting layer and the like. In the organic-light emitting device having this structure, when a voltage is applied between two electrodes, holes from the anode and electrons from the cathode are injected into the organic material layer, and the injected holes and electrons combine with each other to form excitons. When the excitons subsequently drop to the ground state, light is emitted. Such organic light-emitting devices are known to have characteristics, including self-luminescence, high brightness, high efficiency, low driving voltage, wide viewing angle, high contrast and high-speed response properties.
Materials that are used for organic material layers in organic light-emitting devices can be divided, according to function, into light-emitting materials and charge-transporting materials, for example, a hole-injecting material, a hole-transporting material, an electron-transporting material, an electron-injecting material and the like. Further, the light-emitting materials can be divided, according to the emitted color, into blue-, green- and red-emitting materials, and additionally into yellow- and orange-emitting materials, which are required in order to realize more natural colors. Meanwhile, when a single material is used as a light-emitting material, the peak emission wavelength is shifted to a longer wavelength by intermolecular interaction, and the color purity or the efficiency of the device decreases due to the emission attenuation. Thus, in order to increase the color purity and increase the light emission efficiency through energy transfer, a host/dopant system may be used as the light-emitting material.
In order for the organic light-emitting device to sufficiently exhibit the above-described excellent characteristics, materials constituting the organic layers in the device, for example, a hole-injecting material, a hole-transporting material, a light-emitting material, an electron-transporting material, an electron-injecting material and the like, should be supported using stable and efficient materials. However, the development of stable and efficient organic layer materials for organic light-emitting devices is still insufficient. Therefore, the development of novel materials for organic light-emitting devices has been continuously demanded, and the development of novel materials for other organic electronic devices as described above has also been demanded.